FIELD OF THE INVENTION

The present invention relates to an appliance to which one of a plurality of magnetic attachments is attachable.

BACKGROUND OF THE INVENTION

An appliance may have a main unit to which one of a plurality of attachments is attachable. For example, a hair appliance may comprise different attachments for achieving different styling results. In some instances, it may be desirable for the appliance to determine which of the attachments is attached to the main unit.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provided an appliance comprising: a main unit to which one of a plurality of magnetic attachments is attachable in any one of a plurality of rotational positions relative to the main unit about an axis; a magnetometer; and a control module operable to determine which of the plurality of attachments is attached to the main unit based on data output by the magnetometer; wherein the appliance comprises one or more of the following features: (i) the magnetometer is located on the axis; (ii) the appliance comprises the plurality of magnetic attachments, where each magnetic attachment comprises a plurality of magnetic regions distributed about the axis in a rotationally symmetric arrangement, and the magnetometer is located radially inwardly of the plurality of magnetic regions when the attachment is attached to the main unit; and/or (iii) the appliance comprises the plurality of magnetic attachments and wherein each magnetic attachment comprises a magnetic region located on the axis when the attachment is attached to the main unit.

Any one (or indeed combination) of features (i) to (iii) allows for the control module to determine which attachment is attached to the main unit regardless of the rotational position of the attachment. This may, in turn, provide for robust identification of the attachment and/or for flexible use of the attachment. For example, different magnetic attachments may be configured to produce different magnetic fields. However, in each one (or combination) of features (i) to (iii), at least a component of the magnetic field produced by each magnetic attachment in a direction parallel to the axis will be invariant (or nearly so) with respect to the rotational position of the attachment about the axis. This rotationally invariant component may be measured, and different attachments accordingly discriminated, regardless of the rotational position of the attachment. This allows for a robust identification of the attachment, while at the same time allowing for the benefits associated with an attachment that can be attached to the main unit in any one of a plurality of rotational positions (including infinitely many), such as flexibility of use.

Alternatively or additionally to the above benefits, use of the magnetometer according to any one or more of features (i) to (iii) may allow the remote and/or automatic determination of which attachment is attached to the main unit. For example, use of the magnetometer according to any one or more of features (i) to (iii) may allow the determination of which attachment is attached to the main unit to be made remotely from the attachment interface. For example, the magnetic field produced by each attachment (or at least a portion of that magnetic field) may be measurable remotely from the magnetic attachment itself, e.g. at the magnetometer. The attachment interface may otherwise be an undesirable location for sensors to be located due to e.g. packaging constraints and/or harsh conditions such as high temperatures. Therefore, being able to determine, remotely from the attachment interface, which attachment is attached to the attachment interface, may allow for such packaging constraints and/or harsh conditions to be mitigated. Further, use of the magnetometer may allow the determination of which attachment is attached to the main unit to be made automatically, for example as compared to that information being input by a user on a user interface, which may improve user experience.

Optionally, the appliance comprises an electric component and the control module is operable to control the electric component in response to the determination. This may allow for the control module to control the electric component differently for different attachments. This has the benefit that operation of the appliance may be controlled automatically on the basis of the attachment that is in use.

Optionally, the electric component comprises an electric motor or a heater, and the control module is operable to control a speed of the electric motor or a temperature of the heater in response to the determination. The performance of the appliance may be improved by operating the electric motor at different speeds and/or by operating the heater at different temperatures based on the attachment that is in use. For example, the appliance may be a hair appliance, the electric motor may be used to generate an airflow, and the heater may be used to heat the airflow. Different attachments may then provide better drying or styling results at different flow rates and/or at different heat settings. In another example, the appliance may be a vacuum cleaner and the electric motor may be used to generate suction. Different attachments may then perform better at different suctions.

Optionally, the electric component comprises a sensor, and the control module is operable to control a setting of the sensor in response to the determination. Sensors of the appliance may operate more effectively if calibrated according to the attachment being used with the main unit. For example, different attachments for a hair appliance, such as a diffuser and a concentrator, may have different lengths. A ranging sensor, such as a Time-of-Flight sensor, included in the main unit and used to determine the distance from the appliance to a user’s head may therefore, for example, be calibrated differently according to which attachment is being used. For example, the distance at which hair is to be detected by the ranging sensor when a diffuser attachment is in use may be set or calibrated differently to that when a concentrator is being used.

Optionally, the appliance comprises an airflow generator for drawing an airflow through the appliance, and the control module is operable to control a characteristic of the airflow in response to the determination. Different attachments may deliver better results for different airflows. For example, the appliance may be a hair appliance and the attachments may comprise a diffuser and a concentrator. The diffuser may deliver better results when the airflow has lower flow rate. This is because the hair is moved less by the airflow and thus curls are better defined. By contrast, a concentrator may deliver better results when the airflow has a higher flow rate. For example, by employing a higher flow rate, drying and/or styling of the hair may be achieved more rapidly. In another example, the appliance may be a vacuum cleaner and the attachments may comprise a first suction nozzle for use on floors, and a second suction nozzle for use on upholstery. When used on floors, a higher suction may be beneficial to draw in more of the dirt. However, when used on upholstery, a higher suction may cause the upholstery to be sucked into and block the suction nozzle.

Accordingly, better results may be achieved on upholstery with a lower suction.

Optionally, the control module is operable to control one or more of a flow rate and a temperature of the airflow. Similar to that mentioned above, by controlling the flow rate and/or the temperature of the airflow in response to the attachment in use, better overall styling and/or cleaning results may be achieved.

Optionally, the appliance is a hair appliance comprising a plurality of flow and heat settings, and the control module is operable to select one of the settings based on the determination. As noted above, different attachments may deliver better results for different flow and/or heat settings. Accordingly, by selecting one of the plurality of settings based on the attachment in use, better drying and/or styling results may be achieved.

Optionally, the appliance comprises the plurality of magnetic attachments, and the magnetic attachments differ in the magnetic field that each magnetic attachment produces at the magnetometer when the attachment is attached to the main unit. This may allow for a cost- effective means to determine which of the attachments is attached to the main unit. For example, the attachments may anyway comprise magnetic components as a means by which the attachments are attached to the main unit. In other words, a magnetic component of the attachment that is used to attach the attachment to the main unit may also be used by the main unit to determine which attachment it is. Tailoring these magnetic components on each attachment so that they produce different magnetic fields (e.g. net strength and/or direction) at the magnetometer may therefore allow the main unit to identify the attachment without necessarily adding components to the attachments or otherwise requiring adaptation of the form or functionality of the attachments.

Optionally, the magnetic field that each magnetic attachment produces at the magnetometer has a component parallel to the axis, and the component differs for different magnetic attachments. This may allow for a relatively efficient and/or robust means by which to determine the attachment attached to the main unit. For example, the component of the magnetic field parallel to (e.g. along) the axis may be independent of the rotational position of the attachment relative to the main unit, and the attachment may be identified from a relatively simple measurement of the magnetic field in this direction, e.g. by a single axis magnetometer, regardless of the rotational orientation of the attachment.

Optionally, the magnetic attachments each comprise a plurality of magnetic regions, each magnetic region has a positive or negative polarity in the direction of the magnetometer when the magnetic attachment is attached to the main unit, and the magnetic attachments differ in the arrangement of magnetic regions having positive and negative polarities. For example, the arrangement of the magnetic regions having positive and negative polarities may correspond to the number of positive polarity magnetic regions and/or negative polarity magnetic regions, the ratio of positive polarity magnetic regions to negative polarity magnetic regions, the size of the positive polarity magnetic regions and/or negative polarity magnetic regions, and/or the distribution or order of the positive polarity magnetic regions and/or negative polarity magnetic regions. For example, the differing arrangements of magnetic regions between attachments may comprise a differing ratio of magnetic regions having a positive polarity in the direction of the magnetometer when the magnetic attachment is attached to the main unit to magnetic regions having a negative polarity in the direction of the magnetometer when the magnetic attachment is attached to the main unit. Providing different magnetic fields by differing the arrangement of positive and negative polarity magnetic regions may allow for the different attachments to be identified without necessarily altering the magnetic force by which different attachments are attached to the main unit. This may allow for consistency in the attachment and detachment operation across different attachments, which may improve user experience.

Optionally, the magnetic regions are distributed around the circumference of a circle that is centred on the axis when the magnetic attachment is attached to the main unit. This may allow for the attachments to be rotatable about the axis when the attachment is attached to the main unit, whilst still allowing for the attachment to be identified. This may improve flexibility of use of the attachments and/or ease of use of the appliance.

Optionally, the magnetic regions are provided by polarised portions of a bonded magnet. A bonded magnet may, for example, be formed of magnetic particles bound in a binder material. Providing the magnetic regions by polarised portions of a bonded magnet may allow for the magnetic regions to be provided without increasing the magnet part count. For example, the same isotropic bonded magnet part may be used for each attachment, but the isotropic bonded magnet of different attachments may be magnetised according to different polarisation patterns. This may allow for a cost-effective way to provide the magnetic regions.

Optionally, where the magnetometer is located on the axis as per feature (i), the distribution of the polarities of the magnetic regions may be rotationally asymmetric about the axis. This may allow that the rotational position of the magnetic attachment relative to the main unit can be determined, for example by the control module. For example, having a rotationally asymmetric distribution of polarities of magnetic regions may provide that there is a component of the magnetic field at the magnetometer perpendicular to the axis. This may, for example, be measured by the magnetometer, and the control module may determine the rotational position of the attachment based on the angle of the perpendicular component about the axis. Having the distribution of the polarities of the magnetic regions being rotationally asymmetric about the axis may allow for the rotational position to be determined precisely without necessarily altering the magnetic force by which different attachments are attached to the main unit. This may allow for consistency in the attachment and detachment operation across different attachments, which may improve user experience.

Optionally, where the magnetometer is located on the axis as per feature (i), and when one of plurality of magnetic attachments is attached to the main unit, the control module may be operable to additionally determine a rotational position of the magnetic attachment relative to the main unit based on data output by the magnetometer. Use of the magnetometer located on the axis may, for example, allow the rotational position of the attachment to be determined remotely from the attachment interface, which may otherwise be an undesirable location for sensors to be located due to e.g. packaging constraints and/or harsh conditions. This may also allow the rotational position to be determined automatically, for example as compared to being input by a user on a user interface, which may improve user experience. Accordingly, this may allow the rotational position of an attachment relative to the main unit to be automatically and remotely determined.

Optionally, where the magnetometer is located on the axis as per feature (i), the magnetic field produced by the magnetic attachment at the magnetometer when attached to the main unit may have a component perpendicular to the axis, and the control module may be operable to determine the rotational position of the magnetic attachment relative to the main unit based on an angle of the perpendicular component about the axis. This may allow for a cost-effective means to determine the rotational position of the attachment. For example, the attachment may anyway comprise magnetic elements as a means by which the attachments are attached to the main unit. Tailoring these magnetic elements so that they produce a net magnetic field that has a component perpendicular to the axis at the magnetometer may therefore allow the main unit to determine the rotational placement of the attachment without necessarily adding components to the attachment or otherwise requiring adaptation of the form or functionality of the attachments. Moreover, since the perpendicular component is orthogonal to the component parallel to (e.g. along) the axis, the magnetic field produced by the magnetic attachment may serve the dual purpose of allowing the identification of the attachment and allowing the rotational position of the attachment to be determined. This may be cost effective, for example as compared to providing separate means for these separate functions.

Optionally, the appliance comprises an electric component, and the control module is operable to control the electric component according to the determined rotational position. For example, this may be the same electric component as mentioned above, such as a heater or air flow generator. This may allow for the control module to control the electric component differently for rotational positions of an attachment. This has the benefit that operation of the appliance may be controlled automatically on the basis of the rotational position of the attachment relative to the main unit. For example, the rotational position of the attachment relative to the unit may be changed manually by a user and thereby provide a means by which the user may control the appliance to operate in a particular mode. As another example, an attachment orientated at different rotational positions relative to the main unit (and hence relative to e.g. a handle of the main unit) may provide for optimal styling when the appliance is operated differently. Accordingly, this may provide for improved styling.

Optionally, the main unit comprises a barrel section having a central bore, the one of a plurality of attachments is attachable to an end of the barrel section, and the magnetometer is located within the bore. Locating the magnetometer in the bore may allow for the magnetometer to be relatively isolated from heated components of the appliance and/or from other components that may otherwise interfere with the magnetometer. A robust determination of the attachment and/or rotational position of an attachment may therefore be provided. Furthermore, for appliances that already have an existing bore, the magnetometer may be incorporated without increasing the overall size of the appliance or without having to significantly alter the existing packaging of the components in the main unit.

Optionally, at least one of the plurality of attachments is rotatable relative to the main unit about the axis whilst attached to the main unit. This may allow for the user to change the rotational position of the attachment relative to the main unit, which may allow for more flexible use, and further to do so without necessarily removing the attachment from the main unit, which may improve ease of use and overall user experience. In such an appliance it may be particularly useful to allow for attachment identification independent of rotational placement of the attachment and/or remote determination of the rotational placement of the attachment.

Optionally, the appliance is a hair appliance. However, it will be understood that in other examples the appliance may be another type of appliance, such as a vacuum cleaner.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages will now be described, by way of example only, with reference to the accompanying drawings of which:

Figure l is a schematic diagram illustrating a perspective view of an appliance according to an example;

Figure 2 is a schematic diagram illustrating a rear view of a main unit of the appliance;

Figure 3 is schematic diagram illustrating a side section view of the appliance;

Figure 4 is a schematic diagram illustrating a side sectional view of part of the appliance in which an attachment is attached to the main unit;

Figure 5 is a schematic diagram illustrating a perspective view of an attachment according to an example; Figure 6 is a schematic diagram illustrating various distributions of polarities of magnetic regions of magnetic attachments according to an example;

Figure 7 is a schematic diagram illustrating a plot of the magnetic field along the axis at a magnetometer as produced by the various distributions of Figure 6;

Figure 8 is a schematic diagram illustrating various distributions of polarities of magnetic regions of magnetic attachments according to another example;

Figure 9 is a schematic diagram illustrating various distributions of polarities of magnetic regions of magnetic attachments according to yet another example;

Figure 10 is a schematic diagram illustrating various distributions of polarities of magnetic regions of magnetic attachments according to yet still another example;

Figure 11 is a schematic diagram illustrating a perspective view of a magnetic attachment according to another example;

Figure 12 is a schematic diagram illustrating a perspective view of a magnetic attachment according to yet another example;

Figure 13 is a schematic diagram illustrating a perspective view of a magnetic attachment according to still yet another example;

Figure 14 is a schematic diagram illustrating a plot of sensed magnetic field strength against magnet orientation;

Figure 15 is a schematic diagram illustrating a configuration of magnetometer and magnetic attachment according to an example;

Figure 16 is a schematic diagram illustrating a configuration of magnetometer and magnetic attachment according to another example; and

Figure 17 is a schematic diagram illustrating a configuration of magnetometer and magnetic attachment according to yet another example.

Like reference signs denote like features. The axes x, y, z indicated in the Figures correspond amongst the Figures.

DETAILED DESCRIPTION OF THE INVENTION

Referring to Figures 1 to 5, there is illustrated an appliance 102 according to an example. In broad overview, the appliance 102 comprises a main unit 104 to which one of a plurality of magnetic attachments 114, 116 is attachable. Each magnetic attachment 114, 116 is attachable to the main unit 104 in any one of a plurality of rotational positions 115 relative to the main unit 104 about an axis A. The appliance 102 comprises a magnetometer 220 located on the axis A. The appliance 102 comprises a control module 315 operable to determine which of the plurality of magnetic attachments 114, 116 is attached to the main unit 104 based on data output by the magnetometer 220. For example, as described in more detail below, the magnetic attachments 114, 116 may differ in the magnetic field that each magnetic attachment 114, 116 produces at the magnetometer 220 when the attachment 114, 116 is attached to the main unit 104. The magnetometer 220 may measure or otherwise sense this magnetic field and output data indicative of the sensed magnetic field. The control module 315 may map the output data indicative of the sensed magnetic field onto an identifier of one of the plurality of attachments 113, 116, thereby to determine which of the plurality of attachments 114, 116 is attached to the main unit 104.

Locating the magnetometer 220 on the axis A, about which the magnetic attachments 114, 116 may have any one of a plurality of rotational positions 115 (including infinitely many) relative to the main unit 104, allows for the control module 315 to determine which attachment 114, 116 is attached to the main unit 104 regardless of the rotational position 115 of the attachment 114, 116. This may, in turn, provide for robust identification of the attachment 114, 116 and/or for flexible use of the attachment 114, 116. For example, different magnetic attachments 114, 116 may be configured to produce different magnetic fields. However, at least a component of the magnetic field produced by each magnetic attachment 114, 116 along the axis A will be invariant with respect to the rotational position

115 of the attachment 114, 116 about the axis A. Locating the magnetometer 220 on the axis A may allow this rotationally invariant component to be measured, and different attachments 114, 116 to be accordingly discriminated, regardless of the rotational position of the attachment 114, 116. This may allow for a robust identification of the attachment 114, 116, while at the same time allowing for benefits associated with an attachment 114, 116 that can be attached to the main unit 104 in any one of a plurality of rotational positions 115, such as flexibility of use.

Alternatively or additionally to the above benefits, use of the magnetometer 220 located on the axis A may allow the remote and/or automatic determination of which attachment 114,

116 is attached to the main unit 104. For example, use of the magnetometer 220 located on the axis A may allow the determination of which attachment 114, 116 is attached to the main unit to be made remotely from an attachment interface 339. For example, the magnetic field produced by each attachment 114, 116 (or at least a portion of that magnetic field) may be measurable remotely from the magnetic attachment 114, 116 itself, e.g. at the magnetometer 220 located on the axis A. The attachment interface 339 may otherwise be an undesirable location for sensors to be located due to e.g. packaging constraints and/or harsh conditions such as high temperatures. Therefore, being able to determine, remotely from the attachment interface 339, which attachment 114, 116 is attached to the main unit 104, may allow for such packaging constraints and/or harsh conditions to be mitigated. Further, use of the magnetometer 220 may allow the determination of which attachment 114, 116 is attached to the main unit 104 to be made automatically, for example as compared to that information being input by a user on a user interface (not shown), which may improve user experience.

In this example, the appliance 102 is a haircare appliance, and the attachments 114, 116 comprise a concentrator 114 and a diffuser 116 (see e.g. Figure 1).

In some examples, the appliance may comprise an electric component 332, 330, 361 and the control module 315 may be operable to control the electric component 332, 330, 361 in response to the determination of which attachment 114, 116 is attached to the main unit 104. This may allow for the control module 315 to control the electric component 332, 330, 361 differently for different attachments 114, 116. This has the benefit that operation of the appliance 102 may be controlled automatically on the basis of the attachment 114, 116 that is in use.

As one example, the electric component 332, 330, 361 may comprises an electric motor 332 (e.g. used to generate an airflow) or a heater 330 (e.g. used to heat the airflow), and the control module 315 may be operable to control a speed of the electric motor 332 or a temperature of the heater 330 in response to the determination of which attachment 114, 116 is attached. For example, different attachments 114, 116 may provide better drying or styling results at different flow rates and/or at different heat settings. For example, the appliance 102 may comprise an airflow generator 332 for drawing an airflow through the appliance 102, and the control module 315 may be operable to control a characteristic of the airflow in response to the determination. Different attachments may deliver better results for different airflows. For example, the diffuser 116 may deliver better results when the airflow has lower flow rate. This is because the hair is moved less by the airflow and thus curls are better defined. By contrast, the concentrator 114 may deliver better results when the airflow has a higher flow rate. In some examples, the control module 315 is operable to control one or more of a flow rate and a temperature of the airflow. For example, the hair appliance 102 may comprise a plurality of flow and heat settings, and the control module 315 is operable to select one of the settings based on the determination of which attachment 114, 116 is attached to the main unit 104. For example, the control module 315 may store a default flow and temperature setting for each of the attachments 114, 116. Additionally, or alternatively, the control module 315 may store the flow and temperature setting selected by a user when last using a particular attachment 114, 116. As noted above, different attachments may deliver better results for different flow and/or heat settings. Accordingly, by selecting one of the plurality of settings based on the attachment in use, better drying and/or styling results may be achieved. As another example, the control module 315 may be operable to map different user selectable settings onto different operation of the hair appliance 102 based on the determination of which attachment 114, 116 is attached to the main unit 104. For example, in a default mode, user selection of certain settings of flow rate and/or temperature (e.g. ‘low’, ‘medium’ and ‘high’) may correspond to operation of the hair appliance 102 at certain flow rates and/or airflow temperatures. However, the control module 315 may be configured to change the flow rates and/or airflow temperatures to which the selectable settings correspond based on the attachment 114, 116 attached to the main unit 104. For example, the change may be implemented as applying an offset in flow rate and/or temperature to those in the default mode. For example, if the control module 315 determines that a given attachment 114, 116 is attached to the main unit 104 (which attachment is, say, associated with use close to a user’s skin so that use with default mode temperatures may be uncomfortable for a user), the control module 315 may be configured to reduce the temperatures at which the heater 330 is controlled to operate (e.g. via reducing the heater duty cycle and/or reducing a target value for a PID control, for example). More generally, in some examples, the control module 315 may determine the range of temperatures and/or flow rates (or other operation of the hair appliance 102) selectable by a user (i.e. that are able to be selected by a user) based on the attachment 114, 116 that the control module 315 determines to be attached to the main unit 104. For example, so that the range of selectable operation is optimised for the identified attachment 114, 116. As another example, the electric component may be or comprise a sensor 361, and the control module 315 may be operable to control a setting of the sensor in response to the determination. Sensors 361 of the appliance 102 may operate more effectively if calibrated according to the attachment 114, 116 being used with the main unit 104. For example, as shown in Figures 3 and 4, the appliance 102 may comprise a ranging sensor 361, such as a Time-of-Flight sensor 361, included in the main unit 104 and used to determine the distance from the appliance 102 to a user’s head or hair. The different attachments 114, 116 for the hair appliance 102, such as the diffuser 116 and the concentrator 114, may have different lengths. Accordingly, the Time-of-flight sensor 361 may therefore, for example, be calibrated differently according to which attachment 114, 116 is being used. For example, the distance at which hair is to be detected by the ranging sensor 361 when a diffuser attachment 116 is in use may be set or calibrated differently to that when a concentrator 114 is being used.

In some examples, the control module 315 may be operable to set a responsiveness with which the heater 330 and/or airflow generator 332 is turned on or off (or an operating mode thereof adjusted) in response to the determination of which attachment 114, 116 is attached. For example, the responsiveness may be set by altering an algorithmic smoothing applied to the output of the sensor 361, a low pass filter applied to the output of the sensor 361, and/or a delay applied to the change in operating mode of the heater 330 and/or airflow generator 332. For example, some attachments 114 may be typically used in rough drying where the appliance 102 is moved around relatively vigorously during use. In this case (i.e. when it is determined that such an attachment 114, 116 is attached to the main unit 104), it may be desirable to increase an algorithmic smoothing applied to the output of the sensor 361, lower a low pass filter applied to the output of the sensor 361, and/or increase a delay applied to a change in the operating mode of the heater 330 and/or airflow generator 332. This may reduce the chances that said vigorous movement (and hence rapid change in the output of the sensor 361) is erroneously interpreted by the control module 315 as the appliance 102 being moved away entirely from the hair of the user.

In either case, the control module 315 may be operable to control the electric component 332, 330, 361 in response to the determination of which attachment 114, 116 is attached to the main unit 104, which may allow for the operation of the appliance 102 to be controlled automatically on the basis of the attachment 114, 116 that is in use.

In the example illustrated in Figures 1 to 5, the main unit 104 comprises a handle section 110 and a barrel section 106. The handle section 110 is generally cylindrical in shape and comprises a housing 337 that houses the airflow generator 332. The housing comprises an inlet 112 through which an airflow is drawn into the handle section 110 by the airflow generator 332, and an outlet 350 through which the airflow is discharged into the barrel section 106. The airflow generator 332 may comprise, for example, a fan driven by an electric motor.

The barrel section 106 is likewise generally cylindrical in shape, but is shorter in length and wider in diameter than the handle section 110. The barrel section 106 is attached to an end of the handle section 110 and is oriented such that the longitudinal axes of the handle section 110 and the barrel section 106 are orthogonal. As a result, the shape of the main unit 104 resembles a gavel or mallet.

The barrel section 106 comprises a housing 301 that houses the heater 330 and the control module 315. The housing 301 comprises an outer wall 301a and an inner wall 301b that are generally concentric and define a chamber within which the heater 330 and the control module 315 are housed. The housing 301 comprises an inlet 351 through which airflow from the handle section 112 enters the chamber, and an outlet 108 at an end of the barrel section 104 through which the airflow is discharged. The heater 330 is located between the inlet 351 and the outlet 108 and, when powered, heats the airflow. The inner wall 301b defines a bore 334 that extends through the centre of the barrel section 106.

As best seen in Figure 2, the main unit 104 further comprises user controls 222, 224, 226, 228. The user controls 222, 224, 226, 228 are provided on both the handle section 110 and the barrel section 106, and comprise a first button 226 or slider to power on and off the appliance 102, a second button 228 to momentarily power off the heater 330 such that the appliance 102 delivers a cold shot of air, a third button 222 to control the flow rate of the airflow, and a fourth button 224 to control the temperature of the airflow. Alternatively or additionally to the control provided by the control module 315 in response to the determination of which attachment 114, 116 is attached, the control module 315 may control electric components 332, 330, 361 in response to user controls. For example, in response to inputs from the user controls 222, 224, 226, 228, the control module 315 may power on and off the airflow generator 332 and/or the heater 330. Additionally, the control module 315 may control the power or speed of the airflow generator 332 in order to vary the flow rate of the airflow. For example, repeatedly pressing the third button 228 may cause the control module 315 to cycle through different flow rates (e.g., low, medium and high). Similarly, the control module 315 may control the power of the heater 330 in order to vary the temperature of the airflow. For example, repeatedly pressing the fourth button 224 may cause the control module 315 to cycle through different temperature settings (e.g., cold, warm, hot).

Each of the attachments 114, 116 may be attached to an end of the barrel section 106 of the main unit 104. When attached, each of the attachments 114, 116 may be free to rotate relative to the main unit 104 about the central longitudinal axis A of the barrel section 106. The free rotation of the attachments 114, 116 has the advantage that a user is able to achieve a desired direction and angle of airflow without having to hold or manipulate the appliance 102 at uncomfortable angles. In this example, each of the attachments 114, 116 comprises an annular magnet 338, and the barrel section comprises a ferrous ring 336 to which the magnet 338 is attracted to secure the attachment 114, 116 in place. It will be appreciated that the ring 336 need not necessarily be ferrous and may be made of another material to which the magnet 338 is attracted. In this example, when the attachment 114, 116 is attached to the main unit 104, a portion or bung 333 of the attachment 114, 116 is received into the bore 334. In this example, when the attachment 114 is attached to the main unit 104, an airflow expelled from the outlet 108 of the barrel section 106 flows through the attachment and is in turn expelled from an outlet 340 of the attachment 114.

In this example, the magnetometer 220 is located within the bore 334 of the barrel section 106. Specifically, in this example, the magnetometer 220 is provided in a capsule 338 that is located generally centrally of the bore 334. In this example, the capsule 338 is elongate and lies along the axis A. The capsule 338 is connected to the inner wall 301b of the barrel section 106 by a member or fin 335. In this example, the capsule 338 also houses the ranging sensor 361. Locating the magnetometer 220 in the bore 334 and/or in the capsule 338 located within the bore 334 may allow for the magnetometer 220 to be relatively isolated from heated components 330 of the appliance 102 and/or from other components that may otherwise interfere with the magnetometer 220. A robust determination of the attachment 114, 116 may therefore be provided. Furthermore, for appliances that already have an existing bore 334, the magnetometer 220 may be incorporated without increasing the overall size of the appliance 102 or without having to significantly alter the existing packaging of the components in the main unit 104.

As described in more detail below, in some examples the magnetometer 220 is configured to measure or otherwise sense a strength and/or direction of a magnetic field at the magnetometer 220. For example, the magnetometer 220 may be configured to output data indicative of the magnitude and/or direction of the magnetic field at the magnetometer. For example, the magnetometer 220 may be configured to output a magnitude of each of one or more components of the magnetic field at the magnetometer 220 in one or more respective directions, such as along the x, y and/or z axes as indicated in the Figures. The magnetometer 220 may, for example, be provided by one or more Hall effect sensors, although other magnetometers may be used. For example, the magnetometer 220 may be provided by a three axis Hall-effect sensor, for example provided on an integrated chip. The control module 315 may be configured to receive the output data from the magnetometer 220, and determine which attachment 114, 116 is attached to the main unit 104 based on this data. In some examples, the magnetometer 220 and/or the control module 315 may apply a low pass filter and/or averaging to the data output of by magnetometer 220 in order to remove high frequency noise, such as may be produced by components of the appliance 102 such as the heater 330 or the airflow generator 332, or indeed by other electrical devices external to the appliance 102. This may improve the reliability of the determination of which magnetic attachment 114, 116 is attached to the main unit 104.

In this example, the magnetometer 220 is set reasonably far back in the bore 334 of the barrel section 106. In this example, the distance between the magnetometer and the end of the barrel section 104 (i.e., that end to which the attachments 114, 116 attach) is around 45 mm. The magnetometer 220 being set back from the magnetic attachment 114, 116 along the axis A, and specifically set back from the magnet 338 of the magnetic attachment 114, 116, may allow for the magnet 338 to produce a magnetic field at the magnetometer 220 that has a non-zero component along the axis A, which as described in more detail below allow for effective identification of different attachments 114, 116 by the control module 315.

As mentioned, the magnetic attachments 114, 116 may differ in the magnetic field that each magnetic attachment 114, 116 produces at the magnetometer 220 when the attachment 114, 116 is attached to the main unit 104. In the present example, the magnetic field is produced by the magnet 338. That is, the magnet 338 of the attachment 114, 116 that is used to attach the attachment 114, 116 to the main unit 104 is also used to produce the magnetic field that is sensed by the magnetometer 220 and hence on the basis of which the control module 315 determines which attachment 114, 116 is attached to the main unit 104. by the main unit to determine which attachment it is. Tailoring the magnet 338 on each attachment 114, 116 so that they produce different magnetic fields (e.g. net strength and/or direction) at the magnetometer 220 when the attachment 114, 116 is attached to the main unit 104 may therefore allow the main unit 104 to identify the attachment without necessarily adding components to the attachments 114, 116 or otherwise requiring adaptation of the form or functionality of the attachments 114, 116. This may allow for a cost-effective means to determine which of the attachments 114, 116 is attached to the main unit 104.

In some examples, the magnetic field that each magnetic attachment 114, 116 produces at the magnetometer 220 has a component parallel to (e.g. along) the axis A, and this component differs for different magnetic attachments 114, 116. This may allow for a relatively efficient and/or robust means by which to determine the attachment attached to the main unit. For example, the component of the magnetic field parallel to (e.g. along) the axis A will be independent of the rotational position of the attachment 114, 116 relative to the main unit 104, and the attachment may be identified from a relatively simple measurement of the magnetic field regardless of the rotational orientation of the attachment.

As an example, the magnet 338 of different attachments 114, 116 may be of different strengths, which may accordingly result in a magnetic fields at the magnetometer 220 having a component along the axis A of different magnitudes. Alternatively or additionally, the magnet 338 of different attachments 114, 116 may be of different polarities, which may accordingly result in magnetic fields at the magnetometer having a component along the axis A in one direction or an opposite direction and/or with different magnitudes in those directions. Alternatively or additionally, the magnet 338 of different attachments 114, 116 may differ in the direction or angle of polarisation, which may accordingly result in magnetic fields at the magnetometer having a component along the axis A in one direction or an opposite direction and/or with different magnitudes in those directions.

In some examples, the magnetic attachments 114, 116 may each comprise a plurality of magnetic regions 540. For example, the magnet 338 of each attachment 114, 116 may be made up of a plurality of magnetic regions 540. In the example of Figure 5, each magnetic region 540 is provided by an individual magnetic component 540, such as a bipolar magnet. In the example of Figure 5, there are 24 such magnetic regions 540 distributed in a circle centred on the axis A. In this example, the 24 magnetic regions 540 are distributed evenly around the circle centred on the axis A. Distribution of the magnetic regions 540 in a circle centred on the axis A may allow for the attachments 114 to be rotatable about the axis A when the attachment 114, 116 is attached to the main unit 104, whilst still allowing for the attachment 114, 116 to be identified. This may improve flexibility of use of the attachments 114, 116 and/or ease of use of the appliance 102.

In some examples, each magnetic region 540 may have a positive or negative polarity (e.g. its North or South pole, respectively) in the direction of the magnetometer 220 when the magnetic attachment 114, 116 is attached to the main unit 104, and the magnetic attachments 114, 116 differ in the arrangement of magnetic regions 540 having positive and negative polarities. For example, the arrangement of the magnetic regions 540 having positive and negative polarities may correspond to the number of positive polarity magnetic regions 540 and/or negative polarity magnetic regions 540, the ratio of positive polarity magnetic regions 540 to negative polarity magnetic regions 540, the size of the positive polarity magnetic regions 540 and/or negative polarity magnetic regions 540, and/or the distribution or order of the positive polarity magnetic regions 540 and/or negative polarity magnetic regions 540.

As described in more detail below, the differing arrangements of magnetic regions 540 between attachments 114, 116 may comprise a differing ratio of magnetic regions 540 having a positive polarity in the direction of the magnetometer 220 when the magnetic attachment 114, 116 is attached to the main unit 104 to magnetic regions 540 having a negative polarity in the direction of the magnetometer 220 when the magnetic attachment is attached to the main unit 104. For example, each magnetic region 540 may have the same individual magnetic strength, but the arrangement or distribution of polarities of these magnetic regions may differ between attachments 114, 116. Providing different magnetic fields by differing the arrangement of positive and negative polarity magnetic regions 540 may allow for the different attachments 114, 116 to be identified without necessarily altering the magnetic force by which different attachments are attached to the main unit 104. For example, this attachment force may be in the range 10 N to 100 N, for example 50 N. This may allow for consistency in the attachment and detachment operation across different attachments 114, 116, which may improve user experience.

Referring to Figure 6, there is illustrated schematically different arrangements of magnetic regions, according to one example. As per the magnetic regions 540 of Figure 5, in each arrangement there are 24 magnetic regions distributed in a circle. In the example of Figure 6, there are eight different arrangements 602, 604, 608, 610, 612, 614, 616 of magnetic regions. Each different arrangement may, for example, be implemented on a different attachment 114, 116. Accordingly, in this example, the control module 315 may determine which one of eight different attachments 114, 116 is attached to the main unit 104. In Figure 6, each magnetic region is represented by circle. A filled in circle represents that a negative polarity (i.e. South pole, S) is facing towards the magnetometer (not shown) when the attachment (not shown) is attached to the main unit (not shown), and an empty circle represents that a positive polarity (i.e. North pole, N) is facing towards the magnetometer (not shown) when the attachment (not shown) is attached to the main unit (not shown).

In this example, each arrangement 602, 604, 608, 610, 612, 614, 616 has a different number of magnetic regions having a positive polarity N facing towards the magnetometer and a different number of magnetic regions having a negative polarity S facing towards the magnetometer. More particularly, in this example, each arrangement 602, 604, 608, 610, 612, 614, 616 has a different ratio of magnetic regions having a positive polarity N facing towards the magnetometer to magnetic regions having a negative polarity S facing towards the magnetometer. Specifically, in a first arrangement 602 there are 8 N and 16 S (giving a ratio of 8: 16), in a second arrangement 604 there are 6 N and 18 S (giving a ratio of 6: 18), in a third arrangement 606 there are 3 N and 21 S (giving a ratio of 3:21), in a fourth arrangement 608 there are 0 N and 24 S (giving a ratio of (0:24), in a fifth arrangement 610 there are 16 N and 8 S (giving a ratio of 16:8), in a sixth arrangement 612 there are 18 N and 6 S (giving a ratio of 18:6), in a seventh arrangement 614 there are 21 N and 3 S (giving a ratio of 21 :3), and in an eighth arrangement 616 there are 24 N and OS (giving a ratio of 24:0). It is noted that in this example, the distribution of the polarities N,S of the magnetic regions is rotationally symmetric about the axis A, that is, the distribution of the polarities N,S of the magnetic regions of each arrangement 602, 604, 608, 610, 612, 614, 616 has a rotational symmetry of more than one. Specifically, in this example the rotational symmetries of arrangements 602, 604, 608, 610, 612, 614, 616 are 8, 6, 3, 24, 8, 6, 3, and 24 respectively.

Each arrangement 602, 604, 608, 610, 612, 614, 616 produces a different magnetic field at the magnetometer. As indicated in Figure 6, the relative magnetic field strength of the eight arrangements 602, 604, 608, 610, 612, 614, 616 at the magnetometer will be -25, -50, -75, - 100, +25, +50, +75, and +100, respectively. In this example, references to ‘+’ and correspond to magnetic field strengths in one direction (e.g. along the axis A in one direction) and an opposite direction (e.g. along the axis A in the opposite direction) respectively. Figure 7 illustrates a plot of magnetic field strength as measured at the magnetometer 220 as a function of attachments 114, 116 being attached to the main unit 104 having the different arrangements 602, 604, 608, 610, 612, 614, 616 illustrated in Figure 6. Specifically, the plateaus 702, 704, 706, 708, 710, 712, 714, 716 in the magnetic field measurement correspond to attachments being attached to the main unit having the arrangements 602, 604, 608, 610, 612, 614, 616, respectively. As is evident, the eight attachments can be readily discriminated on the basis of the magnetic field. For example, the control module 315 may store eight attachment identifiers each in association with a respective one of these eight magnetic field values. The control module 315 may be configured to determine to which of these eight magnetic field values a current magnetic field value output by the magnetometer 220 corresponds, and accordingly retrieve the associated attachment identifier, thereby to determine which of the plurality of attachments 114, 116 is attached to the main unit.

Although particular arrangements of magnetic regions 540 have been described above, it will be appreciated that in some examples, other arrangements may be used. For example, referring to Figure 8, there is illustrated arrangements 802, 804, 806, 810, 812, 814 of magnetic regions according to another example. The arrangements in this example are similar to those described above with reference to Figure 7, except in the example of Figure 8 there are six rather than 8 arrangements, and the difference between the magnetic field produced by each at the magnetometer 220 is larger . Specifically, in this example, in a first arrangement 802 there are 8 N and 16 S (giving a ratio of 8: 16 and a relative magnetic field strength at the magnetometer of -33.3), in a second arrangement 804 there are 4 N and 20 S (giving a ratio of 4:20 and a relative magnetic field strength at the magnetometer of -66.6), in a third arrangement 806 there are 0 N and 24 S (giving a ratio of 0:24 and a relative magnetic field strength at the magnetometer of -100), in a fourth arrangement 810 there are 16 N and 8 S (giving a ratio of 16:8 and a relative magnetic field strength at the magnetometer of +33.3), in a fifth arrangement 812 there are 20 N and 4 S (giving a ratio of 20:4 and a relative magnetic field strength at the magnetometer of +66.6), and in a sixth arrangement there are 24 N and 0 S (giving a ratio of 24:0 and a relative magnetic field strength at the magnetometer of +100). This arrangement may provide for fewer attachments to be discriminated between, but for a better signal to noise ratio, and therefore for a more robust and/or reliable determination of which attachment 114, 116 is attached to the main unit 104. Of course, it will be appreciated that in some examples, other numbers or ratios of magnetic regions may be used.

In the examples described above with reference to Figures 7 and 8, the distribution of the polarities of the magnetic regions was rotationally symmetric about the axis A. However, in some examples, the distribution of the polarities of the magnetic regions may be rotationally asymmetric about the axis A. For example, the distribution of polarities may have a rotational symmetry of 1. This may allow that the rotational position of the magnetic attachment 114, 116 relative to the main unit 104 can be determined, for example by the control module 315. For example, having a rotationally asymmetric distribution of polarities of magnetic regions may provide that there is a component of the magnetic field at the magnetometer 220 perpendicular to the axis A (see e.g. perpendicular component 513 illustrated schematically in Figure 5). This may, for example, be measured by the magnetometer 220, such a vector magnetometer, and the control module 315 may determine the rotational position of the attachment 114, 116 relative to the main unit 104 based on the angle of the perpendicular component about the axis A (see e.g. angle G illustrated schematically in Figure 5) . Having the distribution of the polarities of the magnetic regions being rotationally asymmetric about the axis A may allow for the rotational position to be determined precisely without necessarily altering the magnetic force by which different attachments 114, 116 are attached to the main unit 104. This may allow for consistency in the attachment 114, 116 and detachment operation across different attachments, which may improve user experience.

Examples of arrangements where the distribution of polarities of the magnetic regions are rotationally asymmetric are illustrated in Figure 9 and 10.

Referring to Figure 9, there are seven arrangements 902, 904, 906, 909, 910, 912, 914 having 9, 6, 3, 12, 15, 18, and 21 positive (N) polarity magnetic regions respectively, 15, 18, 21, 12, 9, 6 and 3 negative (S) polarity magnetic regions respectively, and relative magnetic field strengths at the magnetometer 220 of -25, -50, -75, 0, +25, +50 and +75, respectively. However, the polarities are not distributed symmetrically around the circle, rather in each case, all the positive N polarities are adjacent to one another and all the negative S polarities are adjacent to one another. Accordingly, the magnetic field produced by each arrangement 902, 904, 906, 909, 910, 912, 914 at the magnetometer 220 when the associated attachment 114, 116 is attached to the main unit 104 has a component perpendicular to the axis A.

Referring to Figure 10, there are five arrangements 1002, 1004, 1009, 1010, 1012 having 8, 4, 12, 16, and 20 positive (N) polarity magnetic regions respectively, 16, 20, 12, 8 and 4 negative (S) polarity magnetic regions respectively, and relative magnetic field strengths at the magnetometer 220 of -33.3, -66.6, 0, +33.3, and +66.6 respectively. Again, in this example, the polarities are not distributed symmetrically around the circle rather in each case, all the positive N polarities are adjacent to one another and all the negative S polarities are adjacent to one another. Accordingly, the magnetic field produced by each arrangement 1002, 1004, 1009, 1010, 1012 at the magnetometer 220 when the associated attachment 114, 116 is attached to the main unit 104 has a component perpendicular to the axis A. In this example there are fewer different arrangements but the difference between relative magnetic field strengths between attachments is greater, which may provide for an improved signal to noise ratio and hence a more robust and/or reliable determination of which attachment is attached and/or the rotational position of the attachment 114, 116 relative to the main unit 104. It will be appreciated that in other examples, other arrangements of magnetic regions may be used.

For completeness it is noted that in the examples of Figures 9 and 10, one arrangement 909, 1009 has an equal number of positive polarities (N) ad negative polarities (S). Accordingly, in these cases, the component of the magnetic field produced by the attachment 909, 1009 at the magnetometer 220 in a direction along the axis A may be zero. However, in these examples the attachment 909, 1009 may nonetheless be determined as attached to the main unit 104 based, for example, on the magnetic field produced by the attachment 909, 1009 at the magnetometer 220 in a direction perpendicular to the axis A (which will be non-zero), and discriminated from the other attachments 902, 906, 910, 912, 914 or 1002, 1004, 1010, 1012 by the fact that there is no net magnetic field produced by the attachment 909, 1009 at the magnetometer 220 in the direction of the axis A. It will be appreciated that, in other examples, magnetic fields having a component perpendicular to the axis A at the magnetometer may be produced by other arrangements of one or more magnetic regions.

It is also noted that, in some examples, one or more of the arrangements described above with reference to any one of Figures 6, 8, 9 and 10 may be used in combination. For example, one or more of the arrangements 602 - 616 described above with reference to Figure 6 may be used in combination with one or more of the arrangements 902-914 described above with reference to Figure 9. For example, it is noted that arrangement 612 of Figure 6 and arrangement 912 of Figure 9 both have the same ratio of positive to negative polarity magnetic elements (i.e. 6 S and 18 N). However, the arrangement 612 of Figure 6 is rotationally symmetric (specifically has a rotational symmetry of order 6) and hence the magnetic field it produces at the magnetometer will have a component perpendicular to the axis A, whereas the arrangement 912 of Figure 9 is rotationally asymmetric (specifically has a rotational symmetry of order 1, i.e. has no rotational symmetry) and hence the magnetic field it produces at the magnetometer will have a component perpendicular to the axis A. Accordingly, in this example, the control module 315 may discriminate an attachment 114, 116 having the arrangement 912 from an attachment 114, 116 having the arrangement 612 based on the presence (or not) and/or magnitude of the magnetic field at the magnetometer 220 in a direction perpendicular to the axis A when the attachment 114, 116 is attached to the main body 104. Accordingly, in some examples, the control module 315 may determine which attachment 114, 116 is attached to the main unit based, alternatively or additionally, on the presence and/or a magnitude of a component of the magnetic field in a direction perpendicular to the axis A produced by the magnetic attachment 114, 116 at the magnetometer 220. This may, for example, allow for a larger set of attachments to be discriminated between, for example for the same set of different ratios of positive to negative polarity.

As mentioned, in some examples, when one of plurality of magnetic attachments 114, 116 is attached to the main unit 104, the control module 315 is operable to additionally determine a rotational position 115 of the magnetic attachment 114, 116 relative to the main unit 104 based on data output by the magnetometer 220. For example, the magnetic field produced by the magnetic attachment 114, 116 at the magnetometer 220 when attached to the main unit 104 may have a component 513 perpendicular to the axis A (such as in the examples described above with reference to Figures 9 and 10), and the control module 315 may be operable to determine the rotational position 115 of the magnetic attachment 114, 116 relative to the main unit 104 based on an angle G of the perpendicular component 513 about the axis A. For example, the magnetometer 220 may be configured to determine the magnitude of the magnetic field at the magnetometer 220 along each of the x and y axis (to which the axis A is perpendicular) in the sense of the Figures. The control module 315 may be configured to determine, based on this output data, the angle G of the perpendicular component 513 of the magnetic field about the axis A relative to the main unit 104 (e.g. relative to a reference angle), and from this determine the rotational position 115 of the attachment. For example, the control module 315 may have prestored a plurality of rotational positions each associated with a respective angle G, and when the control module 315 determines that the angle G is or is near a given one of these prestored angle, the control module may map the prestored angle onto the associated prestored rotational position, and thereby determine the rotational position 115 of the attachment 114, 116 relative to the main unit 104.

It will be appreciated that in some examples the control module 315 may be configured to determine which attachment 114, 116 is attached to the main unit 104 and to determine the rotational position 115 of the magnetic attachment 114, 116 relative to the main unit 104 based on data output by the magnetometer 220. For example, the identity of the attachment 114, 116 may be determined based on the magnetic field produced by the attachment at the magnetometer 220 in a direction along the axis A (e.g. along the z axis in the sense of the Figures) for example as described above, and the rotational position 115 may be determined based on the magnetic field produced by the attachment at the magnetometer 220 in a direction perpendicular to the axis A (e.g. along one or both of the x and y axis in the sense of the Figures) for example as described above. For example, the magnetometer 220 may be a vector magnetometer configured to determine the magnitude of the component of the magnetic field at the magnetometer along each of the axis x, y, and z in the sense of the Figures.

Other examples of determining the rotational position may be used. Nonetheless, use of the magnetometer 220 located on the axis A may, for example, allow the rotational position 115 of the attachment 114, 116 to be determined remotely from the attachment interface 339, which may otherwise be an undesirable location for sensors to be located due to e.g. packaging constraints and/or harsh conditions. This may also allow the rotational position

115 to be determined automatically, for example as compared to being input by a user on a user interface, which may improve user experience. Accordingly, this may allow the rotational position 115 of an attachment 114, 116 relative to the main unit 104 to be automatically and remotely determined. Determining the rotational position of the magnetic attachment 114, 116 relative to the main unit 104 based on an angle G of the perpendicular component 513 about the axis A may allow for a cost-effective means to determine the rotational position of the attachment. For example, the attachment 114, 116 may anyway comprise magnetic regions 540 as a means by which the attachments 114, 116 are attached to the main unit 104. Tailoring these magnetic regions 540 so that they produce a net magnetic field that has a component perpendicular to the axis A at the magnetometer 220 may therefore allow the main unit 104 to determine the rotational position of the attachment 114, 116 without necessarily adding components to the attachment 114, 116 or otherwise requiring adaptation of the form or functionality of the attachments 114, 116. Moreover, since the perpendicular component 513 of the magnetic field is orthogonal to the component parallel to (e.g. along) the axis A, the magnetic field produced by the magnetic attachment 114, 116 may serve the dual purpose of allowing the identification of the attachment 114,

116 and allowing the rotational position 115 of the attachment 114, 116 to be determined. This may be cost effective, for example as compared to providing separate means for these separate functions.

As mentioned above, in some examples, the appliance 102 comprises an electric component 330, 332, 361 such as the heater 330, airflow generator 332, or sensor 361. In some examples, the control module 315 may be operable to control the electric component 330, 332, 361 according to the determined rotational position. This may allow for the control module 315 to control the electric component differently for different rotational positions of an attachment 114, 116. This has the benefit that operation of the appliance may be controlled automatically on the basis of the rotational position of the attachment 114, 116 relative to the main unit 104. For example, the rotational position of the attachment 114, 116 relative to the main unit 104 may be changed manually by a user and thereby provide a means by which the user may control the appliance to operate in a particular mode. As another example, an attachment 114, 116 orientated at different rotational positions relative to the main unit 104, 106 (and hence relative to e.g. the handle section 110 of the appliance 102) may provide for optimal styling when the appliance is operated differently. Accordingly, this may provide for improved styling.

In the examples described above with reference to Figure 5, the magnetic regions 540 were provided by individual magnetic component 540, such as individual bipolar magnets 540. However, it will be appreciated that this not necessarily be the case and that in other examples magnetic regions having other forms may be used. For example, Figures 11 and 12 illustrate attachments according to other examples.

Referring to Figure 11, there is illustrated a magnetic attachment 1114 according an example. The magnetic attachment 1114 of Figure 11 is the same as the magnetic attachment 114 described above with reference to Figure 5 (and in some examples may be used in place of the magnetic attachment 114 described above with reference to Figure 5), except that in the example of Figure 11 the magnetic regions 1140 are provided by polarised portions 1140 of a bonded magnet 1138. The bonded magnet 1138 may, for example, be formed of magnetic particles bound in a binder material. The bonded magnet 1138 is annular in shape and is formed of one component. Portions of the bonded magnet 1138 may be polarised according to any of the examples described above with reference to Figures 1 to 10, thereby to provide, for example, the magnetic regions 1140. Providing the magnetic regions 1140 by polarised portions of a bonded magnet 1138 may allow for the magnetic regions 1140 to be provided without increasing the magnet part count. For example, the same isotropic bonded magnet part 1138 may be used for each attachment 114, 116, but the isotropic bonded magnet 1138 of different attachments 114, 116 may be magnetised according to different polarisation patterns. This may allow for a cost-effective way to provide the magnetic regions 1140.

Referring to Figure 12, there is illustrated a magnetic attachment 1214 according to another example. The magnetic attachment 1214 of Figure 12 is the same as the magnetic attachment 114 described above with reference to Figure 5 (and in some examples may be used in place of the magnetic attachment 114 described above with reference to Figure 5), except that in the example of Figure 12 the magnetic regions 1240 are provided in a bung 1233 of the magnetic attachment 114. As mentioned above for the bung 333 of the examples described above with reference to Figures 1 to 5, the bung 1233 of the attachment 1214 of Figure 12 protrudes out from an attachment interface 1239 of the attachment 1214 such that when the attachment 1214 is attached to the main unit 104, the bung 1233 of the attachment 114 is received into the bore of the main unit (see bore 334 in Figure 4). It is to be noted that, for clarity, the bung cover (see bung cover 1135 of bung 1133 in Figure 11) has been removed to show the magnetic regions 1240 housed within. In the example of Figure 12, there are three magnetic regions 1240 provided by three magnetic components such as bipolar magnets 1240 (although in other examples, similar to as described above, the magnetic regions 1240 may be provided e.g. by polarised portions of a bonded magnet (not shown)). The polarities of the magnetic regions 1240 for different attachments (only one attachment 1214 is shown in Figure 12) may have different arrangements, similar to that described above with reference to Figures 1 to 10. In this example, the magnetic regions 1240 may be provided in addition to a magnet (such a magnet is not shown in Figure 12, but see e.g. magnet 338 of attachment 114 in Figure 3) that has the function of attaching the attachment 1214 to the main unit 104. Providing the magnetic regions 1240 as part of the bung 1233 may provide that, when the attachment 1214 is attached to the main unit 104, the magnetic regions 1240 are at a relatively small distance from the magnetometer 220. For example, this may be because they are either a relatively small distance along the axis A from the magnetometer 220 and/or because they are located at a relatively small radial distance from the axis A. This may provide a relatively large magnetic field at the magnetometer 220, which may provide for an improved signal to noise ratio (or equally this may provide that magnetic regions 1240 can have a relatively low magnetic strength whilst not affecting the signal to noise ratio).

In some examples, as per that illustrated in Figure 12, the magnetic regions 1240 may be provided by one or more bipolar magnets 1240 each of which are arranged to have either their positive or negative polarity facing in a direction parallel to the axis A. The magnetic field produced at the magnetometer by different attachments may differ by providing different arrangements of the one or more magnetic regions 1240, such as differing numbers, strengths, polarisations and/or polarisation ratios of the one or more magnetic regions 1240, for example as described above with reference to Figures 1 to 10. However, in some examples, the magnetic field produced at the magnetometer by different attachments may differ by providing one or more magnetic regions having differing polarisation orientations relative to the axis A. An example of this is described with reference to Figure 13.

Referring to Figure 13, there is illustrated a magnetic attachment 1314 according to an example. The magnetic attachment 1314 of Figure 13 is the same as the magnetic attachment 1214 described above with reference to Figure 12 (and in some examples may be used in place of the magnetic attachment 1214 described above with reference to Figure 12), except that in the example of Figure 13 there is one magnetic region 1340 provided by a bipolar magnet 1340 in the bung 1333 of the magnetic attachment 1314 and the bipolar magnet 1340 is angled with respect to the axis A. Specifically, in this example, the positive-negative polarity axis C (i.e. the North-South Axis C) of the bipolar magnet 1340 makes an angle 0 with an axis B passing through the magnet 1340 and which is parallel to the axis A. In some examples, differing magnetic attachments 1314 may have differing angles 9 that the positive-negative polarity axis C of the bipolar magnet 1340 makes with the axis B parallel to the axis A. Specifically, the component of the magnetic field parallel to the axis A (i.e. in the z direction in the sense of the Figures) at the magnetometer 220 may vary according to the angles 9 that the positive-negative polarity axis C of the bipolar magnet 1340 makes with the axis B parallel to the axis A. Accordingly, the control module 315 may determine which magnetic attachment is attached to the main body 104 by mapping the sensed component of the magnetic field parallel to the axis A onto a given attachment 1314. Referring to Figure 14, there is illustrated a plot of magnetic field strength at the magnetometer 220 in a direction along the axis A (i.e. in the z direction in the sense of the Figures) against the angle 0 that the positive-negative polarity axis C of the bipolar magnet 1340 makes with the axis B parallel to the axis A, according to an example. In Figure 14, the data points at angles 0, 45, 90, 135, and 180 degrees are outlined. These angles produce a magnetic field strength at the magnetometer 220 in a direction along the axis A of around -1.9, -1.2, 0, +1.2 and +1.9 Gauss, respectively. In this example, a positive value of magnetic field is associated with orientations where the positive or North pole of the magnet 1340 is facing the magnetometer. Accordingly, there may be, for example, four different magnetic attachments with the magnet 1340 fixed at four different angles 9 of 45, 90, 135, and 180 degrees, respectively. The control module 315 may discriminate between these attachments based on the corresponding different magnetic field strength sensed at the magnetometer 220 in a direction along the axis A -1.9, -1.2, +1.2 and +1.9 Gauss, respectively.

In the examples described above with reference to Figures 13 and 14, the magnetic attachment had one magnet 1340. However, in other examples (not shown), each attachment may have a plurality of the magnets 1340 orientated with a given angle 9. In other examples (not shown), different arrangements of magnets 1340 having differing orientations, or differing combinations or orientation, in order to produce respective different magnetic fields at the magnetometer 220 in a direction along the axis A may be used.

In the examples described above with reference to Figures 13 and 14, the magnetic region 1340 is provided by a bipolar magnet 1340 that is angled with respect to the axis A. However, as mentioned above, in other examples, the magnetic region(s) 1340 may be provided by polarised portions of a bonded magnet (not shown). For example, the magnetic region(s) 1340 may be provided by one or more regions of an bonded or sintered magnet to which a high voltage magnetizer impulse is applied in order to polarise the magnetic material thereof with a positive-negative polarity axis C having a given angle 9. This may provide, for example, that each attachment may be manufactured having the same bonded magnet part (for example embedded in the same plastic support in the same way), but the bonded magnet part of different attachments may then be magnetised so as to have a positivenegative polarity axis C making different angles 9 with the axis A (e.g. by applying the high voltage magnetizer impulse in different orientations relative to the bonded magnet part). This may reduce the cost and complexity of manufacturing the magnetic attachments, for example as compared to different attachments comprising a bipolar magnet embedded in a plastic support in different ways so to have a positive-negative polarity axis C making different angles 0 with the axis A.

In the examples described above with reference to Figures 1 to 14, the appliance 102 was a hair appliance 102. However, it will be appreciated that this need not necessarily be the case and that in other examples the appliance may be another type of appliance, such as a vacuum cleaner. Further, in the above examples certain numbers of attachments 114, 116 were referred to but it will be appreciated that, in some examples, any plurality of attachments 114, 116 may be used. Further, in the above examples, certain forms of attachments 114, 116 and/or certain magnets 338 or arrangements of magnetic regions 540, 1140, 1240 are referred to but it will be appreciated that this need to necessarily be the case and that in in some examples, any magnetic attachment 114, 116 attachable in any one of a plurality of rotational positions relative to the main unit 104 about an axis A may be used. Further, although in the above examples certain configurations, locations, and functions of the magnetometer 220 and the control module 315 are described, it will be appreciated that these need not necessarily be the case and that in some examples the appliance may comprise any magnetometer located on the axis A and any control module 315 operable to determine which of the plurality of attachments 114, 116 is attached to the main unit 104 based on data output by the magnetometer 220. As such, it will be appreciated that, in some examples, there may be provided an appliance 102 comprising: a main unit 104 to which one of a plurality of magnetic attachments 114, 116 is attachable in any one of a plurality of rotational positions 115 relative to the main unit 104 about an axis A; a magnetometer 220 located on the axis A; and a control module 315 operable to determine which of the plurality of attachments 114, 116 is attached to the main unit 104 based on data output by the magnetometer 220.

In the examples described above with reference to Figures 1 to 14, the magnetometer 220 is located on the axis A, and as a result the control module 315 can determine which of the plurality of attachments 114, 116 is attached to the main unit 104 irrespective of the rotational position of the attachment 114, 116 relative to the main unit 104. However, there are other examples where the control module 315 may determine which attachment 114, 116 is attached to the main unit 104 irrespective of the rotational position of the attachment 114, 116 relative to the main unit 104, but where the magnetometer 220 is not necessarily located on the axis A. Two such examples are described with below with reference to Figures 16 and 17.

Referring firstly to Figure 15, there is a diagram illustrating, in schematic overview, an example configuration that is according to the examples described above with reference to Figures 1 to 14. Specifically, as described above, the magnetic attachment 114, 1114, 1214, 1314 (which in this example has a magnetic region 540, 1140, 1240, 1340) is attachable to the main unit of an appliance (only the magnetometer 220 of the main unit is shown in Figure 15) in any one of a plurality of rotational positions relative to the main unit about an axis A, and the magnetometer 220 is located on the axis A. As described above, the component of the magnetic field produced by the magnetic attachment 114, 1114, 1214, 1314 at the magnetometer 220 along the axis A does not change with rotational position of the attachment 114, 1114, 1214, 1314 about the axis A. Accordingly, locating the magnetometer 220 on the axis A ensures that the magnetic attachment 114, 1114, 1214, 1314 can be identified irrespective of the rotational position of the attachment about the axis A.

Referring now to Figure 16, there is a diagram illustrating a configuration according to other examples. In these other examples, similarly to the examples described above, a magnetic attachment 1614 (having a magnetic region 1640) is attachable to a main unit of an appliance (only the magnetometer 220’ of the main unit is shown in Figure 16) in any one of a plurality of rotational positions relative to the main unit about an axis A. Indeed, in these examples, the attachment 1614, the magnetic region 1640, the magnetometer 220’, the main unit, and/or any other feature of the appliance (not shown in Figure 16) may be the same or similar to those of the examples described above with reference to Figures 1 to 15. However, in these other examples described with reference to Figure 16, the magnetic region 1640 of the magnetic attachment 1614 is located on the axis A. In these other examples, the magnetometer 220’ need not necessarily be located on the axis A (although it may be), and indeed in the example of Figure 16 the magnetometer 220’ is radially offset from the axis A. However, nonetheless, locating the magnetic region 1640 on the axis A may ensure that the location of the magnetic region 1640 relative to the magnetometer 220’ does not change with rotational position of the attachment 1614 about the axis A when the attachment 1614 is attached to the main unit (not shown) and hence that the magnetic field produced by the magnetic region 1640 at the magnetometer 220’ does not change with rotational position of the attachment 1614 about the axis A. Accordingly, locating the magnetic region 1640 on the axis A ensures that the magnetic attachment 1614 can be identified irrespective of the rotational position of the attachment about the axis A (and without the magnetometer 220’ necessarily being located on the axis A, although it can be).

Referring now to Figure 17, there is a diagram illustrating a configuration according to yet other examples. In these other examples, similarly to the examples described above, a magnetic attachment 1714 (having magnetic regions 1714) is attachable to a main unit of a an appliance (only the magnetometer 220” of the main body is shown in Figure 17) in any one of a plurality of rotational positions relative to the main unit about an axis A. Indeed, in these examples, the attachment 1714, the magnetic regions 1740, the magnetometer 220”, the main unit, and/or any other feature of the haircare appliance (not shown in Figure 17) may be the same or similar to those of the examples described above with reference to Figures 1 to 15. However, in these other examples described with reference to Figure 17, the magnetic attachment 1714 comprises a plurality of magnetic regions 1740 distributed about the axis A in a rotationally symmetric arrangement, and the magnetometer 220” is located radially inwardly of the plurality of magnetic regions 1740 when the attachment is attached to the main unit. In these other examples, the magnetometer 220” need not necessarily be located on the axis A (although it can be), and indeed in the example of Figure 17 the magnetometer 220” is radially offset from the axis A. However, nonetheless, the magnetometer 220” being located radially inwardly of the plurality of magnetic regions 1714 distributed about the axis A in a rotationally symmetric arrangement, may ensure that the component of the magnetic field produced by the magnetic regions 1714 parallel to the axis A at the magnetometer 220’ ’ does not change (or changes only to a limited extent) with rotational position of the attachment 1714. Specifically, with this arrangement, the different offsets of the different magnetic regions 1740 from the magnetometer 220” in different rotational positions of the attachment 1714 are balanced out in the component of the magnetic field at the magnetometer 220” in a direction parallel to the axis A (i.e. in the z direction in the sense of the Figures) - the movement of a given magnetic region 1740 towards the magnetometer 220” when the rotational position changes is balanced by the movement of the magnetic region 1740 on the opposite side of the distribution to the given magnetic region 17140 away from the magnetometer 220’. This is the case as long as the magnetometer 220” is radially inward of the magnetic regions 1740 and the magnetic regions 1740 are distributed about the axis A in a rotationally symmetric arrangement. Accordingly, this may ensure that the magnetic attachment 1714 can be identified irrespective of the rotational position of the attachment about the axis A.

In the examples described with reference to Figure 17, the magnetic regions 1740 may be distributed in a rotationally symmetric arrangement in the sense that the arrangement of magnetic regions 1740 may have a rotational symmetry of order greater than 1. In other words, in these examples, each given magnetic region 1740 of the distribution may have a corresponding magnetic region 1740 on the opposite side of the axis A that is the same as the given magnetic region 1740 (i.e. has the same properties, e.g. magnetic strength, physical size, polarity). For example, examples of a plurality of magnetic regions distributed in a rotationally symmetric arrangement about the axis A include, for example, the arrangements 602-616 described above with reference to Figure 6, and the arrangements 802-814 described above with reference to Figure 8. Other rotationally symmetric arrangements may be used.

It is noted that, in the examples described with reference to Figure 17, depending on the precise configuration of the magnetic regions 1740 and the magnetometer 220” (within the constraint that the magnetometer 220” is located radially inward of a rotationally symmetric distribution of magnetic regions 1740), the component of the magnetic field in a direction parallel to the axis at the magnetometer 220” may not vary at all with rotation of the attachment 1714 about the axis A or may vary only to a limited extent with rotation of the attachment 1714 about the axis A, for example within a range of magnitudes. However, in the latter case the control module 315 may nonetheless determine which of a plurality of such magnetic attachments 1714 is attached to the main unit irrespective of the rotational position of the attachment 1714 by, e.g. matching the measured component of the magnetic field produced by a given magnetic attachment 1714 in a direction parallel to the axis A at the magnetometer 220” to a given one of a plurality of stored ranges of values, where each stored range of values is associated with a different magnetic attachment 1714. Accordingly, in either case, the magnetic attachment 1714 can be identified irrespective of the rotational position of the attachment about the axis A.

Accordingly, it will be appreciated that all of the examples described above with reference to Figures 1 to 17 allow for the control module to determine which of a plurality of magnetic attachments 114, 1114, 1214, 1314, 1614, 1714 is attached to a main unit of an appliance irrespective of the rotational position of the attachment relative to the main unit about the axis A. Accordingly, it will be appreciated that there may be provided an appliance comprising: a main unit to which one of a plurality of magnetic attachments is attachable in any one of a plurality of rotational positions relative to the main unit about an axis; a magnetometer; and a control module operable to determine which of the plurality of attachments is attached to the main unit based on data output by the magnetometer; and that the appliance may comprises one or more of the following features: (i) the magnetometer is located on the axis (e.g. as per the examples described above with reference to Figures 1 to 15); (ii) the appliance comprises the plurality of magnetic attachments, where each magnetic attachment comprises a plurality of magnetic regions distributed about the axis in a rotationally symmetric arrangement, and the magnetometer is located radially inwardly of the plurality of magnetic regions when the attachment is attached to the main unit (e.g. as per the examples described above with reference to Figure 17); and/or (iii) the appliance comprises the plurality of magnetic attachments and wherein each magnetic attachment comprises a magnetic region located on the axis when the attachment is attached to the main unit (e.g. as per the examples described above with reference to Figure 16). Any one (or indeed combination) of features (i) to (iii) allow for the control module to determine which of a plurality of magnetic attachments is attached to a main unit irrespective of the rotational position of the attachment relative to the main unit about the axis A. This may, in turn, provide for robust identification of the attachment and/or for flexible use of the attachment. In some examples, the appliance may include the features according to any one or combination of the examples described above with reference to Figures 1 to 17.

Whilst particular examples are described above, it should be understood that these are illustrative only and that various modifications may be made without departing from the scope of the invention as defined by the claims.